704 A MANUAL OF BACTERIOLOGY 



with the water to be examined before taking the speci- 

 men. Care must be taken not to soil the stopper of the 

 bottle, which should be tied down with a thin layer of 

 cotton- wool enclosed between two pieces of muslin, and 

 the bottle should be not quite filled. In taking the speci- 

 men the following details should be observed : 



(1) If taken from a tap, the water should be allowed 

 to flow for five minutes before the specimen is collected. 



(2) The water from a cistern is not representative of 

 the water-supply ; to be so the specimen must be taken 

 direct from the main. 



(3) If taken from a stream or pond, the bottle should be 

 held about a foot below the surface and away from the 

 edge before the stopper is removed. 



(4) If taken from a well the conditions should be noted, 

 e.g. whether the well has been recently disturbed or 

 not, whether the pumps have been in operation, etc., 

 for such factors may influence the number of bacteria 

 found. 



The specimen should then be examined with as little 

 delay as possible, for if allowed to stand for any time a 

 large increase in the number of bacteria may take place. 

 Frankland, for example, found that in distilled water, 

 even at the ordinary temperature, organisms multiply 

 enormously : 



Hours. Organisms per c.c. 



1,073 



6 6,028 



24 7,262 



48 48,100 



In water of good quality the organisms are found to 

 multiply much more rapidly during the first few days, 

 after which time they become less and less numerous ; 

 but in impure water multiplication is slower, and the 



